Excitation-Contraction Coupling in Skeletal Muscle [Part 2/2]

The video explains the process of muscle contraction, focusing on the role of calcium in the sarcoplasm and the function of the sarcomere. It details the proteins involved, such as actin, myosin, tropomyosin, and troponin, and describes the crossbridge formation and cycle. The video also covers the termination of muscle contraction through calcium removal and acetylcholine degradation.

What is the primary role of calcium in muscle contraction?

• To bind to myosin directly

• To initiate the release of acetylcholine

• To bind to troponin and facilitate crossbridge cycling

• To provide energy for the power stroke

Which protein acts as a gatekeeper by holding tropomyosin over the binding sites on actin?

• Myosin

• Troponin

• Actin

• Calcium

What must be bound to myosin for crossbridge formation to occur?

• Tropomyosin

• ADP and phosphate

• Calcium

• ATP

During the power stroke, what happens to the myosin head?

• It releases calcium

• It binds to ATP

• It rotates and pulls the thin filament

• It detaches from actin

What causes the detachment of myosin from actin?

• Release of ADP

• Hydrolysis of ATP

• Binding of calcium to myosin

• Binding of ATP to myosin

What is the role of acetylcholinesterase in muscle contraction?

• To hydrolyze ATP

• To initiate the power stroke

• To degrade acetylcholine and help terminate contraction

• To bind calcium to troponin

What triggers the release of calcium from the sarcoplasmic reticulum?

• Hydrolysis of ATP

• Detachment of myosin from actin

• Action potential reaching the transverse tubule

• Binding of ATP to myosin